1. Field of the Invention
The present invention relates to a thermal processing roller for subjecting a member to be processed such as a resin film to a heating processing or a heat-absorbing processing by using fluid as heat transfer medium, and relates to a temperature control apparatus for the roller.
2. Description of the Related Art
In general, when a member to be processed such as a resin film is applied to a roller, the member is heated to a predetermined temperature or the member at a high temperature is cooled to a predetermined temperature while the member is abutted against and passes through the roller. In the case of performing the heating processing, the roller is heated to a temperature necessary for the heating processing. In contrast, in the case of performing the heat-absorbing processing, since the temperature of the roller itself increases due to heat absorbed from the member to be processed, the roller is cooled to a temperature suitable for the cooling processing thereof. In each case, medium for carrying or transferring heat is required, and fluid such as oil is used for the medium. That is, the fluid at a suitable temperature is passed within the roller, whereby roller is heated or heat is absorbed from the roller by using the fluid.
FIG. 12 shows the schematic configuration of an example of such a thermal processing roller apparatus. In FIG. 12, 1 depicts a roll shell constituting a roller main body, 2 a rotation driving shaft which is rotated by a not-shown motor to rotate the roll shell, 3 an inner core, 4 a rotary joint, 5 an oil storage tank, 6 oil (heat transfer fluid), 7 a heat exchanger (for heating or cooling), 8 a pump, 9 a temperature sensor, 10 a temperature control apparatus, 11 an electric power control circuit, 12 a heater and 13 a member to be processed such as a resin film which abuts against the roll shell and passes therethrough. The roll shell 1 is configured in a cylindrical shape. The inner core 3 is disposed within the hollow portion of the roll shell and a heat transfer medium flowing path 3a is formed within the inner core 3 so as to pass through the center portion thereof. The heat transfer medium flowing path 3a is coupled to the inflow port of the rotary joint 4 through the inner portion of the rotation driving shaft 2. A heat transfer medium flowing path 1a formed between the inner peripheral wall of the roll shell 1 and the outer peripheral wall of the inner core 3 is coupled to the outlet of the rotary joint 4 through the inner portion of the rotation driving shaft 2.
That is, the oil 6 within the oil storage tank 5 is heated or cooled to the predetermined temperature when passing through the heat exchanger 7. Then, the oil 6 is sent within the roll shell 1 by the pump 8, then flows through the heat transfer medium flowing paths 3a, 1a and is exhausted into the oil storage tank 5. At the time of heating the member to be processed 13, the oil 6 is heated by the heater 12 within the heat exchanger 7 and the oil 6 thus heated passes through the heat transfer medium flowing paths 3a, 1a within the roll shell 1. Thus, the roll shell 1 is heated, so that the member to be processed 13 abutting against the surface of the roll shell 1 is heated by the heat of the roll shell or the heat is absorbed from the member to be processed.
The temperature sensor 9 for detecting the temperature of the oil (heat transfer fluid) thus flown is provided at the output side of the heat exchanger 7. A detected temperature signal from the temperature sensor 9 is sent to the temperature control apparatus 10. A setting temperature S (see FIG. 13) for setting the temperature of the oil 6 thus flown is inputted in the temperature control apparatus 10 in advance. The temperature control apparatus compares the setting temperature S with the detected temperature signal thus inputted from the temperature sensor 9 and sends a control signal corresponding to the deviation therebetween to the electric power control circuit 11 constituted by a thyristor etc. The electric power control circuit 11 supplies electric power corresponding to the control signal to the heater 12. Thus, the heater 12 is heated by the electric power thus supplied to heat the heat transfer fluid 6 to the setting temperature S and maintain the heated temperature.
In such a thermal processing heater, there arises a difference between the temperature of the heat transfer fluid flowing into the roller (formed by coupling the rotation driving shaft to the roll shell) and the temperature of the heat transfer fluid flowing therefrom after heating the member to be processed or absorbing heat from the member to be processed. The temperature difference appears on the surface of the roller, so that there arises a problem that the thermal processing can not be performed uniformly as to the member to be processed abutting against the surface of the roller, in the longitudinal direction of the member to be processed along the axis core of the roller. In order to obviate such a problem, in the related technique, a flow rate of the heat transfer fluid flowing within the roller is increased in accordance with the magnitude of the temperature difference in order to reduce the temperature difference. Thus, there arises a problem that the heat exchanger for heating or cooling and the pump become inevitably larger.
Further, according to such the temperature control for the heat transfer fluid 6, as shown in FIG. 13, initially, the rising rate of the surface temperature T2 of the roll shell 1 is lower as compared with the rising rate of the temperature T1 of the heat transfer fluid 6, so that a time period t1 required for the surface temperature T2 of the roll shell 1 to increase near the setting temperature S becomes long. In particular, when an amount of the heat transfer fluid 6 flowing within the roll shell 1 is small, the heat transfer rate at the heat transfer surface (inner surface) of the roll shell 1 through which the heat transfer fluid 6 flows becomes low, so that the time period tends to be longer.
Furthermore, as shown in FIG. 13, there arises a deviation d1 between the surface temperature T2 of the roll shell 1 and the temperature T1 of the heat transfer fluid 6 due to such a fact that the temperature of the heat transfer fluid 6 controlled at the setting temperature S reduces at a pipe provided on the way of the flow, or that a temperature difference is caused within the thick portion from the heat transfer surface (inner surface) to the surface (outer surface) of the roll shell 1 through which the heat transfer fluid 6 flows. When the member to be processed 13 abuts against and passes through the surface of the roll shell 1, since the member to be processed 13 absorbs the heat from the surface of the roll shell, the surface temperature of the roll shell reduces, so that the deviation becomes a larger value d2. In order to prevent such a phenomenon, a flow rate of the heat transfer fluid 6 is required to increase. As a result, there arises a problem that the heat exchanger and the pump are required to be larger.